Local corticosteroid application blocks transmission in normal nociceptive C‐fibres

Abstract

The effect of a locally applied depot form of a corticosteroid on the electrical properties of nerves was investigated in an experimental model. The segmental transmission in electrically stimulated A-fibres and in C-fibres of the plantar nerve in the anaesthetized rat was utilized. A drop of methylprednisolone acetate or vehicle constituent was placed on the dissected plantar nerve proximal to the stimulating electrodes after recording control responses (A-fibre volley in the sciatic nerve and C-fibre evoked reflex discharge in flexor motoneurons). The corticosteroid was found to suppress the transmission in thin unmyelinated C-fibres but not in myelinated A-beta fibres. The effect was found to be due to the corticosteroid per se. The effect was reversed when the corticosteroid was removed, which suggests a direct membrane action.

Cervical interlaminar epidural steroid injection for neck pain and cervical radiculopathy: effect and prognostic factors

“…Much research supports the rationale for the use of steroid injections for the management of sciatica [13][14][15][16][17]. Painful symptoms of herniated disc diseases are commonly thought to be due to inflammatory changes compressing a nerve root or inflammation of the longitudinal ligaments of the spine [18][19][20].…”

Eficacia analgésica de una dosis única de dexametasona perineural en el bloqueo ecoguiado del nervio femoral en cirugía de prótesis total de rodilla

“…Sin embargo, la dexametasona prolonga el efecto analgésico en bloqueos nerviosos del plexo braquial [22][23][24][25][26][27][28][29][30] y del nervio ciático 31,32 sin efectos secundarios. Esta propiedad parece ser debida a que por un lado, la dexametasona atenúa los mediadores de la respuesta inflamatoria producida por la cirugía, al disminuir la descarga neuronal ectópica e inhibir los canales de potasio dependientes de las fibras C-Nociceptivas [33][34][35][36] , y por otro lado a su poder de vasoconstricción 31 , disminuyendo por tanto la absorción de los AL.…”

The effect of epidurally administered dexamethasone with lignocaine for post-operative analgesia in dogs undergoing ovariohysterectomy. A dose-response study

“…The exact mechanism of this analgesic effect is not understood 12 , but several mechanisms have been suggested to explain it 13,14 . Inhibition of phospholipase A2 and cyclooxygenase-2 expression by steroids during inflammation reduces prostaglandin synthesis and subsequently decreases the hyperalgesia associated with acute nociception during surgery 15 .…”